1. Field of the Invention
The present invention relates to an ink for ink jet recording and an ink jet recording method which can produce a high-quality printed image on various recording media, for example, plain papers, recycled papers, and coat papers.
2. Background Art
Ink jet recording is a method wherein an ink composition is ejected as a droplet through a fine nozzle to record letters or figures onto the surface of a recording medium. Ink jet recording systems which have been developed and put to practical use include: a method wherein an electric signal Is converted to a mechanical signal using an electrostrictive element to intermittently eject an ink composition reservoired in a nozzle head section, thereby recording letters or symbols on the surface of a recording medium and a method wherein an ink composition, reservoired in a nozzle head section, in its portion very close to the ejection portion is rapidly heated to create a bubble and the ink composition is intermittently ejected by volume expansion created by the bubble to record letters or symbols on the surface of a recording medium.
Properties required of ink compositions used in the above ink jet recording are such that the drying property of the print is good, no feathering is created, good printing can be performed on various recording media, and, in the case of multi-color printing, color-to-color intermixing does not occur.
In particular, prevention of feathering is important for realizing a high-quality image. Paper is likely to create feathering because it comprises fibers that are different from each other or one another in ink penetration. In particular, this tendency is significant for recycled paper because it comprises various fibers having different ink penetration. For this reason, in order to prevent he feathering, various proposals has been made on a reduction in penetration of the ink composition into recording media or an improvement in drying speed of the printed ink image.
For example, Japanese Patent Publication 2907/1990 proposes utilization of glycol ether as a wetting agent, Japanese Patent Publication 15542/1989 proposes utilization of a water-soluble organic solvent, and Japanese Patent Publication 3837/1990 proposes utilization of a glycol ether as a dye solubilizer.
Further, in order to improve the penetrability of an ink for ink jet recording, U.S. Pat. No. 5,156,675 proposes addition of diethylene glycol monobutyl ether, U.S. Pat. No. 5,183,502 proposes addition of Surfynol 465 (manufactured by Nissin Chemical Industry Co., Ltd. ) as an acetylene glycol surfactant, and U. S. Pat. No. 5,196,056 discloses addition of both diethylene glycol mono-n-butyl ether and Surfynol 465. Furthermore, U. S. Pat. No. 2,083,372 studies and teaches utilization of an ether of diethylene glycol as an ink composition. In this connection, diethylene glycol mono-n-butyl ether is known as butylcarbitol to those skilled in the art, and detailed description thereon is given, for example, in U.S. Patent No. 3,291,580.
For regulating the penetrability of the ink composition containing a pigment, for example, Japanese Patent Laid-Open No. 147861/1981 discloses utilization of a pigment and triethylene glycol monomethyl ether in combination. Japanese Patent Laid-Open No. 111165/1997 discloses utilization of a pigment and an ether of ethylene glycol, diethylene glycol, or triethylene glycol in combination.
On the other hand, a method has been proposed wherein an ink composition is printed on a heated recording medium to rapidly evaporate the solvent component, thereby permitting the ink composition to be rapidly fixed onto the recording medium. Heating, however, is likely to have an adverse effect on recording media, particularly paper. Further, this method involves an additional disadvantage of increased power consumption by heating.